1. Technical Field of the Invention
This invention relates to the field of devices used for materials testing, and specifically for testing plated test specimens by applying static tension loads to the specimens for extended periods of time. The purpose of such testing is to detect hydrogen embrittlement damage incurred during plating processes.
2. Prior Background Art
The prior art is comprised of devices generally designed for stress or creep rupture testing. See FIG. 1 which shows a typical prior art device, traditionally referred to as a lever arm tester. The device consists of a lever arm of from twelve to twenty inches in length, pivotally supported on a fixed vertical member at a point along the lever arm's length between its center and an end to which the top of a test specimen is attached. The bottom end of the test specimen is attached to a fixed base plate. When weights are applied to the opposite end of the lever arm, tensile force is exerted on the test specimen as dictated by the formula t=(wl)/d, where t is the tensile force exerted on the test specimen, w is the weight applied to the far end of the lever arm, 1 is the distance between the lever arm pivot point and the end carrying the applied weights, and d is the distance between the lever arm pivot point and the end connected to the test specimen. The applied force, t, causes testing of the specimen to take place.
Prior art devices are inferior in several respects to the present invention. The twelve to twenty inches long lever arm, size, and shape of these devices require considerable floor space be reserved in testing laboratories which often have limited available floor space. Prior art testers are completely manual in operation, and must be operated by a technician skilled in the testing procedure because of their many variables and potential inaccuracies. The devices are capable of testing only one specimen, or one group of specimens, at a time, and are typically very costly.
Thus, there exists a need for a static load testing device that overcomes the problems and limitations of the prior art. The present invention is compact, easy to use, and relatively inexpensive. It requires considerably less floor space than conventional devices, and has the capacity to test multiple specimens simultaneously. This device is substantially more accurate than prior art devices, and is equipped with electronic load readouts and timers for increased efficiency and decreased reliance on manual adjustments and readings; as such, it can be operated by semi-skilled personnel. Additionally, a simple screw mechanism is used to apply tensile force to test specimens, eliminating the need for cumbersome weights.